Indentation testing of composite materials: a novel approach to measuring interfacial characteristics and engineering properties

Findings made through the indentation testing of composites are presented in this thesis. The concept was developed as an attempt to evaluate the interfacial shear strength at a mesolevel, possibly overcoming the deficiencies of present techniques. Vickers Microhardness Testing and Continuous Ball Indentation Testing (CBIT) of composite materials provided data for assessing the sensitivity of indentation techniques to interfacial characteristics and engineering properties. Both methods proved capable of discerning the level of fiber-matrix adhesion. The CBIT presented the greatest potential for making quantitative measures of interfacial shear strength. A unique micromechanics model of the contact situation predicted failure events and trends consistent with the observed data from the CBIT. The present elastic model predicted an interfacial shear strength slightly higher than those reported in the literature. However, the interface strength obtained through the CBIT provides more of an engineering assessment of the interfacial quality when compared to other techniques. Both experimental and analytical results suggest that indentation testing of composites is most sensitive to shearing characteristics of the system. Vickers and ball penetration results displayed some correlation to global laminate properties. Vickers hardness shows a close relationship to IITRI compression strength only when fiber compressive failure is observed in the laminate test. The CBIT provides the best opportunity for exploring fiber composite stress-strain information.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Engineering Mechanics

Department dc:contributor.department

Engineering Mechanics

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1991

Author dc:creator

• Lesko, John J.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-03172010-020329

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/41677